The skin forms a primary interface with the environment, with the keratinocyte a critical component of the innate immune system. Perturbation of healthy skin can lead to inflammation through cutaneous immune responses. As such, the immunology of skin is an important focus of a SBDRC with ?The Keratinocyte and its Microenvironment? as its theme. he skin immune system entails an interactive set of innate and adaptive immune cells that can be studied in situ, taken apart for studies at the single cell level, or reconstructed to recreate immune conditions of the skin. The objective of the Translational and Experimental Skin Testing and Immune Tracing (TEST IT) Core is to support and promote the research of SBDRC scientists interested in human and murine cutaneous immune responses in health and disease. The Core will isolate various immune cells from healthy and diseased skin, including at the single cell level, and offer preparative services for the characterization of these cells directly or in functional assays. Using Vectra multispectral imaging equipment, the Core will assist in designing experiments allowing in situ monitoring of human and mouse skin samples, explants and engineered skin. The Core will provide guidance for the efficient expansion of immune cells from skin and blood to be recombined with 3D reconstituted human skin or explants by the Skin Tissue Engineering and Morphology (STEM Core). Prior to reconstruction, cells can be genetically manipulated with products from the Gene Engineering, Transduction and Nanotechnology (GET iN) Core. These engineered keratinocyte-immune cell models will then be available for further immune assessment. A unique and highly novel aspect of the TEST IT core will be to provide a skin challenge facility for in vivo monitoring. This will be accomplished through a dedicated clinical unit and staff to test exposure to environmental agents that affect skin immunologically, whether in a potentially deleterious way, such as ultraviolet/UV light, or in a beneficial way, such as topical medications that suppress immune responses. The Core will oversee the Tissue Acquisition Program (TAP), which obtains archival samples, as well as fresh skin, blood, and other samples (including through the in vivo skin challenge facility) for a central biorepository with secure records; coded, deidentified tissues are distributed to scientists for use in individual laboratories or the service Cores. The Core will also maintain a roster of healthy volunteers and individuals with skin disease who are willing to participate in IRB-approved, skin challenge experiments. These translational studies support mechanistic investigations and provide proof-of-concept data. The Core also focuses on training the research community about immunodermatology, offering expertise in designing mouse and human experiments involving the skin immune system and generating course material in immunodermatology, immunotherapeutics, and immune monitoring. This is a novel core that focuses on enabling investigators to perform advanced and highly translational immune skin research. The ability to study perturbed human skin in a controlled manner will greatly facilitate translational research.